Chemical Analysis of CsPbBr2X (X = Cl, I) Nanocomposites by Total Reflection X-Ray Fluorescence Spectroscopy (TXRF)

An approach to TXRF determination of the composition of perovskite nanocomposites of the putative compositions CsPbBr 2 Cl and CsPbBr 2 I is proposed. Sample preparation consists in the treatment of hydrophobic samples with dimethylformamide (DMFA) and the subsequent dilution of the obtained solutions with water. When using a copper solution as an internal standard, the reproducibility of the results of TXRF determination of the elements is attained with S r no more than 0.05. The validity of the determination of Cs, Pb, Br, and I is confirmed by the results of their determination by ICP-MS in solutions after processing samples in DMFA followed by dilution with 2% HNO 3 for Cs, Pb, and Br or tetramethylammonium hydroxide (TMAH) for Cs, Pb, Br, and I, whereas the determination of chlorides is confirmed by the method of direct potentiometry in diluted solutions. It is shown that lead does not form insoluble chlorides in the TMAH solution and does not interfere with the determination. The effect of bromides on the determination of chlorides is characterized by a potentiometric coefficient of 10 –3 . The results obtained provide the determination of the stoichiometry of the synthesized compounds CsPbBr 2 Cl and CsPbBr 2.7 I 0.3 .